In the chemical reaction, the material that can change the chemical reaction rate (increase or decrease) of reactants without changing the chemical equilibrium, and its quality and chemical properties have not changed before and after the chemical reaction is called catalyst (solid catalyst is also called catalyst). According to statistics, more than 90% of industrial processes use catalysts, such as chemical, petrochemical, biochemical, environmental protection and so on. [1] There are many kinds of catalysts, which can be divided into liquid catalyst and solid catalyst according to the state of reaction system; homogeneous catalyst and heterogeneous catalyst according to the state of reaction system, homogeneous catalyst includes acid, alkali, soluble transition metal compound and peroxide catalyst. Catalyst plays an extremely important role in modern chemical industry. For example, iron catalyst is used in ammonia production, vanadium catalyst is used in sulfuric acid production, and different catalysts are used in ethylene polymerization and butadiene rubber production.

The activation of some catalysts is simple and rapid, such as the reduction of nickel oxide in methanation catalysts, the valence change of metal oxides in some oxidation catalysts, etc. The activation of some catalysts is complex and time-consuming. For example, the ammonia synthesis catalyst is a strong Fe3O4 solid solution containing a small amount of aluminum and calcium atoms. It takes 5-10 days to reduce it to active α - Fe, which affects the effective start-up time of the plant. The catalyst manufacturer can reduce it to α - Fe in advance, and then use inert gas containing trace oxygen to cover α - Fe with a layer of iron oxide film. The oxidized α - Fe only accounts for about 10% of the total iron atoms. This can not only ensure the safety of transportation and loading process, but also save the recovery time. For example, the reduction temperature of NiO / Al2O3 catalyst for hydrogenation of benzene or phenol is 300-350 ℃, while the industrial reactor can only reach 180-220 ℃, and it can also be pre reduced in the catalyst factory. Other catalysts can be treated similarly. In catalyst manufacturing, it is called catalyst pre activation (or pre reduction, pre sulfurization), and the corresponding catalyst is called pre activation catalyst, or pre reduction catalyst, pre sulfurization catalyst.

The storage and transportation of catalyst are usually packed in iron drums lined with airtight plastic bags. During transportation, especially when boarding, alighting and shipping, it is necessary to avoid the operation that damages the packaging container or its sealing. Most catalysts absorb vapor from the air due to chemical or physical reasons (such as capillary condensation), resulting in the decrease of mechanical strength and activity. Most of the catalysts are inorganic compounds. If they are well sealed, they can be stored for decades without changing their performance. A few catalysts (such as pre reduced metal catalysts and some metal organic compounds) will produce hydrogen when they meet or interact with water. They should be kept dry and placed in a well ventilated warehouse